Rotary energy recovery devices have been used for many decades. For example, patent applications filed in the 1960s showed constructions of such energy recovery devices wherein a multichannel rotor revolved within an exterior housing. In many of these early constructions, such as those shown in U.S. Pat. Nos. 3,431,747; 3,582,090 and 3,910,587, the rotor channels were of circular cross-section and balls were employed that would shift from near one end of the channel to near the other to reasonably effectively seal the channel to deter the mixing of the two fluids at an interface therebetween. These energy recovery devices were usually driven by a drive shaft extending from one end of the rotor through the use of a suitable electric motor or the like, using a belt or gear drive or the like. Later U.S. patents to Hauge, such as U.S. Pat. Nos. 4,887,942; 5,338,158 and 5,988,993 improved upon these earlier devices and avoided the need for use of balls or other sliding stoppers within the rotor channels. Moreover, in the '993 patent, for example, the liquids entering the device are used to create torque to drive the rotor, i.e. the liquid flow serves as the driving force for the energy recovery device. Such a drive concept is relied upon in the constructions shown in many later U.S. patents and published patent applications and is generally found in energy recovery units sold by the assignee of this application, Energy Recovery, Inc.
Very generally, the reliance upon the fluids, generally liquids flowing through the rotor to provide the rotary torque has been achieved through the construction of entrance and exit passageways in end covers through which the fluid enters into and exits from the rotors. These end covers can provide tangential flow vectors to accomplish this desired end, as described in the '993 patent and in U.S. Pat. Nos. 6,540,487, 7,221,557 and 7,306,437.
Illustrative of the foregoing is U.S. Pat. No. 6,540,487 wherein a rotor is illustrated similar to the cylindrical rotor 3 shown in FIG. 1 which contains twelve channels 5 that extend axially through the rotor from end face 6 to end face. The channels have openings 7, 9 at opposite ends and are all similar in shape. Each of the channels 5 has a pair of straight sidewalls of equal dimension that are aligned generally radially with respect to the axis or centerline of the rotor 3. End covers are employed that contain oblique ramps in the inlet and outlet passageways which cause the fluid to enter into and exit from the channels 5 with a directional vector in a manner such as to create torque upon the rotor 3 that causes it to revolve clockwise, as viewed in FIG. 1 and indicated by the reference arrow 4. As a result of such revolution in a clockwise direction, the sidewall of the channel opening that is leading is marked 7L and the sidewall that is trailing is marked 7T. This structure is essentially illustrative of rotary energy recovery devices upon which the present invention improves.
The patents more recent than the '993 patent provide evidence of various improvements in the art of rotary energy recovery devices, and work has continued to seek further improvements in the operation of devices of this character.